“History is the trade secret of science fiction, and theories of history are its invisible engine. One such theory is that society evolves because people’s relationship with nature tends to change more radically and rapidly than their relationships with each other. Technology outpaces law and custom. From this mismatch, upheavals ensue. Society either moves up to a new stage with more scope for the new technology, or the technology is crushed to fit the confines of the old society. As the technology falls back, so does the society, perhaps to an earlier configuration. In the main stream of history, however, it has moved forward through a succession of stages, each of which is a stable configuration between the technology people have to work with, and their characteristic ways of working together. But this stability contains the seeds of new instabilities. Proponents of this theory argue that the succession of booms and slumps, wars, revolutions and counter-revolutions, which began in August 1914 and which shows no prospect of an end, indicates that we live in just such an age of upheaval.”